Medina J, Bargues M, Terol J, Pérez-Alonso M, Salinas J
Departamento de Mejora Genética y Biotecnología, Instituto Nacional de Investigaciones Agrarias y Alimentarias, Carretera de la Coruña, Km. 7, 28040 Madrid, Spain.
Plant Physiol. 1999 Feb;119(2):463-70. doi: 10.1104/pp.119.2.463.
We have identified two genes from Arabidopsis that show high similarity with CBF1, a gene encoding an AP2 domain-containing transcriptional activator that binds to the low-temperature-responsive element CCGAC and induces the expression of some cold-regulated genes, increasing plant freezing tolerance. These two genes, which we have named CBF2 and CBF3, also encode proteins containing AP2 DNA-binding motifs. Furthermore, like CBF1, CBF2 and CBF3 proteins also include putative nuclear-localization signals and potential acidic activation domains. The CBF2 and CBF3 genes are linked to CBF1, constituting a cluster on the bottom arm of chromosome IV. The high level of similarity among the three CBF genes, their tandem organization, and the fact that they have the same transcriptional orientation all suggest a common origin. CBF1, CBF2, and CBF3 show identical expression patterns, being induced very rapidly by low-temperature treatment. However, in contrast to most of the cold-induced plant genes characterized, they are not responsive to abscisic acid or dehydration. Taken together, all of these data suggest that CBF2 and CBF3 may function as transcriptional activators, controlling the level of low-temperature gene expression and promoting freezing tolerance through an abscisic acid-independent pathway.
我们从拟南芥中鉴定出了两个与CBF1高度相似的基因。CBF1是一个编码含AP2结构域转录激活因子的基因，该转录激活因子可与低温响应元件CCGAC结合，并诱导一些冷调节基因的表达，从而提高植物的抗冻性。我们将这两个基因命名为CBF2和CBF3，它们同样编码含有AP2 DNA结合基序的蛋白质。此外，与CBF1类似，CBF2和CBF3蛋白也包含推定的核定位信号和潜在的酸性激活结构域。CBF2和CBF3基因与CBF1连锁，在第四条染色体的短臂上构成一个基因簇。三个CBF基因之间的高度相似性、它们的串联排列方式以及具有相同的转录方向这一事实，均表明它们有着共同的起源。CBF1、CBF2和CBF3表现出相同的表达模式，经低温处理后会迅速被诱导表达。然而，与大多数已鉴定的冷诱导植物基因不同的是，它们对脱落酸或脱水无反应。综上所述，所有这些数据表明，CBF2和CBF3可能作为转录激活因子发挥作用，通过一条不依赖脱落酸的途径控制低温基因的表达水平并提高抗冻性。
